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Flora Fact: Eye of the Buck

It’s not a peach. It’s not a redbud. Well, it’s not a true buckeye either.

By Dyanne Fry Cortez

The Mexican buckeye tree is most easily identified by its unusual fruit. The three-lobed hanging capsules are green in summer, turning brown in fall. After splitting open to release their seeds, dry shells may remain on bare branches through the winter months.

The dark, shiny seed is about a half-inch in diameter and roughly spherical. A pale scar marks the spot where it attached to the capsule wall. Although smaller, it bears a striking resemblance to the “buckeye” produced by Ohio’s state tree. However, Ungnadia speciosa is not a true buckeye. It’s in a genus all its own.

Mexican buckeye is native to northern Mexico, New Mexico and the drier, rockier parts of Texas. If you hike canyon trails, you may find it growing at the foot of a cliff or clinging to rocks alongside a steep descent. It’s typically a small tree, 15 feet or shorter, many-branched and multi-trunked. If it finds a sheltered spot with plenty of water, this species can grow as tall as 30 feet.

Fragrant, rose pink flowers appear in spring, usually just ahead of the new leaves. At a distance, it’s easy to mistake a blooming Mexican buckeye for a peach or a redbud, which flower around the same time. Seen up close, the flowers are as distinctive as the fruit. They appear lopsided, with four petals on top and a fifth that hangs below the long, drooping stamens. The blooms attract bees and certain types of butterflies, but they don’t last long.

Mexican buckeye leaves are pinnately compound, with leaflets in pairs along a central stem. A typical leaf will be about a foot long, with six to eight paired leaflets and one more at the tip. Individual leaflets are 2 to 3 inches long, with pointed ends and slightly toothed edges. The deep green foliage hangs gracefully from the many branches, offering dappled shade for hikers and wild animals, and turns lemon yellow in fall.

The seeds and leaves are mildly toxic, although some small mammals can eat them. For humans, Mexican buckeye is just part of the scenery: a hardy, drought-tolerant Texas native that’s attractive in all seasons.

Common Names: Mexican buckeye

Scientific Name: Ungnadia speciosa

Size: From 8 to 30 feet tall, depending on soil

Did You Know? The name originates from hetuck, a Native American word for "buck eye," which the seed was thought to resemble